5(6)-Carboxyrhodamine 110 is a useful synthetic intermediate in the synthesis of 4,5-Disulfo Rhodamine-123 Carboxylic Acid Succinimidyl Ester Lithium Salt (D678830); a xanthene dye substituted two times by a sulfonic acid used as fluorescent probes, particularly in biological samples. It is more photostable than fluorescein.